Characterization of uranium(VI) sorption by organobentonite

The U(VI) sorption on the bentonite modified by hexadecyltrimethylammonium bromide (HDTMA) was studied in the concentration range: 0.0001-0.001 mol/dm3 in the aqueous phase and in the pH range: 3-10. The experiments concerning the pH influence on the molar absorption coefficient cb of U(VI) in the bentonite phase showed that the species: UO22+, UO2(OH)+, UO2(OH)2 UO2(OH)3-, UO2(OH)42-, (UO2)3(OH)5+, (UO2)3(OH)7-, present in the aqueous phase, are responsible for uranium sorption. Their sorption parameters K were determined and it is evident that for higher concentrations of HDTMA+ cations in the bentonite phase, i.e. for b96-b157 bentonite, the presence of anionic species: UO2(OH)3-, UO2(OH)42-, and (UO2)3(OH)7- in the aqueous phase results in the increase of U(VI) molar absorption coefficient cb in the sorbent phase.